1. Field of the Invention
The present invention relates to a motor and more particularly to an AC motor.
2. Description of the Related Art
The conventional AC motor is not easily added new electronic control means due to the bulky and heavy motor, and thus is replaced by the DC motor gradually. AC voltage is first transformed into DC voltage and then a DC motor is driven by the DC voltage via a full bridge converter or a half bridge converter. At present, the AC voltage transformed into the DC voltage by a full-wave rectifier or half-wave rectifier, but the performance is not good and easily causes undesired power consumption.
BRIEF SUMMARY OF THE INVENTION
An embodiment of the invention provides an AC motor driven by an AC voltage. The AC motor comprises a motor coil, a switch circuit, a position detector, a controller and an AC/DC transformer. The motor coil receives the AC voltage. The switch circuit is electrically connected to the motor coil and controls a current passing through the motor coil. The position detector comprises a Hall element and detects a position of a rotor and outputting a polarity signal. The controller receives the polarity signal from the position detector, and controls the switch circuit to make the current be a first current with a first direction or a second current with a second direction according to the AC voltage and the polarity signal, wherein the first direction is opposite to the second direction. The AC/DC transformer converts the AC voltage into a DC voltage and outputs the DC voltage to the controller and the position detector.
An embodiment of the invention provides an AC motor driven by an AC voltage. The AC motor comprises a first motor coil, a second motor coil, a switch circuit, a position detector, a controller and an AC/DC transformer. The first motor coil and the second motor coil receive the AC voltage. The switch circuit is electrically connected to the first motor coil and the second motor coil to control a first current passing through the first motor coil or a second current passing through the second motor coil. The position detector comprises a Hall element to detect a position of a rotor and outputting a polarity signal. The controller receives the polarity signal from the position detector, and controls the switch circuit to make the current be the first current with a first direction or the second current with a second direction according to the AC voltage and the polarity signal, wherein the first direction is opposite to the second direction. The AC/DC transformer converts the AC voltage into a DC voltage and outputs the DC voltage to the controller and the position detector.
A detailed description is given in the following embodiments with reference to the accompanying drawings.